In Firefox, position: relative; doesn't work for table cells. Content positioned absolutely inside a table cell with position: relative; will be positioned in relation to the nearest positioned ancestor outside the table, instead of the table cell itself.

Any idea if there's any way to get Firefox to honour position: relative on the table cell?

Correct. From the spec: "The effect of 'position:relative' on table-row-group, table-header-group, table-footer-group, table-row, table-column-group, table-column, table-cell, and table-caption elements is undefined." — Olly Hodgson over 8 years ago

Ah yes, I saw someone mention that, wasnt sure if it was true. Good old specs. — Paul D. Waite over 8 years ago